1. Field of the Invention
This invention relates to a three-dimensional netted structure used for a cushioning material and the like, and a method of and an apparatus for manufacturing the same.
2. Brief Description of the Related Arts
Known methods of manufacturing a void-carrying three-dimensional netted structure include a method disclosed in Japanese Pat. Publ. KOKOKU No. S50-39185, or a method disclosed in Japanese Pat. Laid-Open KOKAI No. S60-11352, etc., which is adapted to manufacture resin cotton on which polyester fibers are bonded with a bonding agent made of, for example, a rubber-based material. There are also methods of or apparatuses for manufacturing a void-carrying three-dimensional netted structure by entangling resin threads by endless belts, and such methods or apparatuses include the invention disclosed in Japanese Pat. Laid-Open KOKAI No. H11-241264, etc.
However, the demands for a product of such a three-dimensional netted structure have been diversified. It is necessary that each of netted structures manufactured be finished to one of different shapes by cutting or molding the netted structures to demanded shapes in a later stage of the manufacturing stage. This causes a product finishing operation to become very complicated.
A three-dimensional netted structure manufactured by a prior art method becomes low in density in some cases. Since both surface portions of a bundle contact belt conveyors, outer surfaces of the bundle are substantially flattened. However, left and right end surfaces of the bundle have an irregular, helical shape, and side surfaces thereof have a laterally wavy non-straight shape.
The endless belts mentioned above by which a resin threads are entangled is liable to be damaged due to the heat, etc., so that there is a fear of encountering a problem concerning the durability of the endless belts.
Therefore, the invention provides a method of and an apparatus for manufacturing a three-dimensional netted structure, capable of rendering it unnecessary to carry out a finishing operation in a later stage, improving the degree of straightness of the side surfaces of the netted structure, meeting a demand for finishing the netted structure to modified shapes, and improving the durability of the netted structure.